1 files changed, 263 insertions, 0 deletions
diff --git a/arch/arm/common/mcpm_entry.c b/arch/arm/common/mcpm_entry.c
new file mode 100644
index 00000000000..370236dd1a0
--- /dev/null
+++ b/arch/arm/common/mcpm_entry.c
@@ -0,0 +1,263 @@
+/*
+ * arch/arm/common/mcpm_entry.c -- entry point for multi-cluster PM
+ *
+ * Created by:  Nicolas Pitre, March 2012
+ * Copyright:   (C) 2012-2013  Linaro Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/irqflags.h>
+
+#include <asm/mcpm.h>
+#include <asm/cacheflush.h>
+#include <asm/idmap.h>
+#include <asm/cputype.h>
+
+extern unsigned long mcpm_entry_vectors[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER];
+
+void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr)
+{
+	unsigned long val = ptr ? virt_to_phys(ptr) : 0;
+	mcpm_entry_vectors[cluster][cpu] = val;
+	sync_cache_w(&mcpm_entry_vectors[cluster][cpu]);
+}
+
+static const struct mcpm_platform_ops *platform_ops;
+
+int __init mcpm_platform_register(const struct mcpm_platform_ops *ops)
+{
+	if (platform_ops)
+		return -EBUSY;
+	platform_ops = ops;
+	return 0;
+}
+
+int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster)
+{
+	if (!platform_ops)
+		return -EUNATCH; /* try not to shadow power_up errors */
+	might_sleep();
+	return platform_ops->power_up(cpu, cluster);
+}
+
+typedef void (*phys_reset_t)(unsigned long);
+
+void mcpm_cpu_power_down(void)
+{
+	phys_reset_t phys_reset;
+
+	BUG_ON(!platform_ops);
+	BUG_ON(!irqs_disabled());
+
+	/*
+	 * Do this before calling into the power_down method,
+	 * as it might not always be safe to do afterwards.
+	 */
+	setup_mm_for_reboot();
+
+	platform_ops->power_down();
+
+	/*
+	 * It is possible for a power_up request to happen concurrently
+	 * with a power_down request for the same CPU. In this case the
+	 * power_down method might not be able to actually enter a
+	 * powered down state with the WFI instruction if the power_up
+	 * method has removed the required reset condition.  The
+	 * power_down method is then allowed to return. We must perform
+	 * a re-entry in the kernel as if the power_up method just had
+	 * deasserted reset on the CPU.
+	 *
+	 * To simplify race issues, the platform specific implementation
+	 * must accommodate for the possibility of unordered calls to
+	 * power_down and power_up with a usage count. Therefore, if a
+	 * call to power_up is issued for a CPU that is not down, then
+	 * the next call to power_down must not attempt a full shutdown
+	 * but only do the minimum (normally disabling L1 cache and CPU
+	 * coherency) and return just as if a concurrent power_up request
+	 * had happened as described above.
+	 */
+
+	phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset);
+	phys_reset(virt_to_phys(mcpm_entry_point));
+
+	/* should never get here */
+	BUG();
+}
+
+void mcpm_cpu_suspend(u64 expected_residency)
+{
+	phys_reset_t phys_reset;
+
+	BUG_ON(!platform_ops);
+	BUG_ON(!irqs_disabled());
+
+	/* Very similar to mcpm_cpu_power_down() */
+	setup_mm_for_reboot();
+	platform_ops->suspend(expected_residency);
+	phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset);
+	phys_reset(virt_to_phys(mcpm_entry_point));
+	BUG();
+}
+
+int mcpm_cpu_powered_up(void)
+{
+	if (!platform_ops)
+		return -EUNATCH;
+	if (platform_ops->powered_up)
+		platform_ops->powered_up();
+	return 0;
+}
+
+struct sync_struct mcpm_sync;
+
+/*
+ * __mcpm_cpu_going_down: Indicates that the cpu is being torn down.
+ *    This must be called at the point of committing to teardown of a CPU.
+ *    The CPU cache (SCTRL.C bit) is expected to still be active.
+ */
+void __mcpm_cpu_going_down(unsigned int cpu, unsigned int cluster)
+{
+	mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_GOING_DOWN;
+	sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu);
+}
+
+/*
+ * __mcpm_cpu_down: Indicates that cpu teardown is complete and that the
+ *    cluster can be torn down without disrupting this CPU.
+ *    To avoid deadlocks, this must be called before a CPU is powered down.
+ *    The CPU cache (SCTRL.C bit) is expected to be off.
+ *    However L2 cache might or might not be active.
+ */
+void __mcpm_cpu_down(unsigned int cpu, unsigned int cluster)
+{
+	dmb();
+	mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_DOWN;
+	sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu);
+	dsb_sev();
+}
+
+/*
+ * __mcpm_outbound_leave_critical: Leave the cluster teardown critical section.
+ * @state: the final state of the cluster:
+ *     CLUSTER_UP: no destructive teardown was done and the cluster has been
+ *         restored to the previous state (CPU cache still active); or
+ *     CLUSTER_DOWN: the cluster has been torn-down, ready for power-off
+ *         (CPU cache disabled, L2 cache either enabled or disabled).
+ */
+void __mcpm_outbound_leave_critical(unsigned int cluster, int state)
+{
+	dmb();
+	mcpm_sync.clusters[cluster].cluster = state;
+	sync_cache_w(&mcpm_sync.clusters[cluster].cluster);
+	dsb_sev();
+}
+
+/*
+ * __mcpm_outbound_enter_critical: Enter the cluster teardown critical section.
+ * This function should be called by the last man, after local CPU teardown
+ * is complete.  CPU cache expected to be active.
+ *
+ * Returns:
+ *     false: the critical section was not entered because an inbound CPU was
+ *         observed, or the cluster is already being set up;
+ *     true: the critical section was entered: it is now safe to tear down the
+ *         cluster.
+ */
+bool __mcpm_outbound_enter_critical(unsigned int cpu, unsigned int cluster)
+{
+	unsigned int i;
+	struct mcpm_sync_struct *c = &mcpm_sync.clusters[cluster];
+
+	/* Warn inbound CPUs that the cluster is being torn down: */
+	c->cluster = CLUSTER_GOING_DOWN;
+	sync_cache_w(&c->cluster);
+
+	/* Back out if the inbound cluster is already in the critical region: */
+	sync_cache_r(&c->inbound);
+	if (c->inbound == INBOUND_COMING_UP)
+		goto abort;
+
+	/*
+	 * Wait for all CPUs to get out of the GOING_DOWN state, so that local
+	 * teardown is complete on each CPU before tearing down the cluster.
+	 *
+	 * If any CPU has been woken up again from the DOWN state, then we
+	 * shouldn't be taking the cluster down at all: abort in that case.
+	 */
+	sync_cache_r(&c->cpus);
+	for (i = 0; i < MAX_CPUS_PER_CLUSTER; i++) {
+		int cpustate;
+
+		if (i == cpu)
+			continue;
+
+		while (1) {
+			cpustate = c->cpus[i].cpu;
+			if (cpustate != CPU_GOING_DOWN)
+				break;
+
+			wfe();
+			sync_cache_r(&c->cpus[i].cpu);
+		}
+
+		switch (cpustate) {
+		case CPU_DOWN:
+			continue;
+
+		default:
+			goto abort;
+		}
+	}
+
+	return true;
+
+abort:
+	__mcpm_outbound_leave_critical(cluster, CLUSTER_UP);
+	return false;
+}
+
+int __mcpm_cluster_state(unsigned int cluster)
+{
+	sync_cache_r(&mcpm_sync.clusters[cluster].cluster);
+	return mcpm_sync.clusters[cluster].cluster;
+}
+
+extern unsigned long mcpm_power_up_setup_phys;
+
+int __init mcpm_sync_init(
+	void (*power_up_setup)(unsigned int affinity_level))
+{
+	unsigned int i, j, mpidr, this_cluster;
+
+	BUILD_BUG_ON(MCPM_SYNC_CLUSTER_SIZE * MAX_NR_CLUSTERS != sizeof mcpm_sync);
+	BUG_ON((unsigned long)&mcpm_sync & (__CACHE_WRITEBACK_GRANULE - 1));
+
+	/*
+	 * Set initial CPU and cluster states.
+	 * Only one cluster is assumed to be active at this point.
+	 */
+	for (i = 0; i < MAX_NR_CLUSTERS; i++) {
+		mcpm_sync.clusters[i].cluster = CLUSTER_DOWN;
+		mcpm_sync.clusters[i].inbound = INBOUND_NOT_COMING_UP;
+		for (j = 0; j < MAX_CPUS_PER_CLUSTER; j++)
+			mcpm_sync.clusters[i].cpus[j].cpu = CPU_DOWN;
+	}
+	mpidr = read_cpuid_mpidr();
+	this_cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
+	for_each_online_cpu(i)
+		mcpm_sync.clusters[this_cluster].cpus[i].cpu = CPU_UP;
+	mcpm_sync.clusters[this_cluster].cluster = CLUSTER_UP;
+	sync_cache_w(&mcpm_sync);
+
+	if (power_up_setup) {
+		mcpm_power_up_setup_phys = virt_to_phys(power_up_setup);
+		sync_cache_w(&mcpm_power_up_setup_phys);
+	}
+
+	return 0;
+}